Underground formation testing is performed during drilling and geotechnical investigation of underground formations. The testing of such underground formations is important as the results of such examinations may determine, for example, if a driller proceeds with drilling and/or extraction. Since drilling operations are expensive on a per day basis, excessive drilling impacts the overall economic viability of drilling projects.
Multi-valve well testing tools use multiple valves configured in a circuit. Toggling of one of the valves typically sets the other valves into motion as well. The well testing tools disclosed in U.S. Pat. No. 4,553,598 to Meek entitled “Full Bore Sampler Valve Apparatus”, and in U.S. Pat. No. 4,576,234 to Upchurch entitled “Full Bore Sampler Valve”, are mechanical in nature. One valve is disposed in the tool and is mechanically linked to another valve disposed in the tool. To open one valve, an operator at the well surface, upon opening the valve, must expect the other valve to open or close, since the two valves are mechanically linked together. Therefore, the operation of one valve is not independent of the operation of the other valve. When one valve in the tool is opened, other valves disposed in the tool must be opened or closed in a specific predetermined sequence.
More recent multi-valve well testing tools use other arrangements for toggling valves. For example, semi-passive valves are referenced in U.S. Pat. No. 7,527,070 to Brennan, III et al., the entirety of which is incorporated herein by reference. Brennan, III et al. disclose valves that are partially passive wherein the flow of fluid through the valve assists in toggling the valve. Hydraulics are only used in the referenced system to assist in returning the valve-state to its original position. The hydraulic valve systems of the prior art do not use hydraulics to initially set the valve or valves into motion. Moreover, the valve systems are not fully active. That is, all aspects of valve movement are not controlled by hydraulics. To provide a valve system that is fully active, a solenoid is required for each individual valve. Space is limited in a downhole tool, and each solenoid requires a relatively large amount of space.
Therefore, a need exists for providing a system and/or method that uses hydraulic pressure to toggle valve state while minimizing size and/or the number of solenoids required.